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| United States Patent |
5,776,642
|
|
Tahon
, et al.
|
July 7, 1998
|
Method for manufacturing a multicolor filter array element
Abstract
A method is provided for manufacturing a multicolour filter array element,
firmly associated with a transparent electrode layer in a multicolour
liquid crystal display device, comprising a silver halide colour
photographic material wherein the colour processing of the silver halide
colour material comprises a treatment of the colour processed colour
material in a solution comprising at least one group III metal ion. The
processing method diminishes the yellowing, due to heating, of the
processed photographic silver halide colour material.
| Inventors:
|
Tahon; Jean-Pierre (Leuven, BE);
Loccufier; Johan (Zwijnaarde, BE);
Van Gorp; Herman (Tielen, BE);
Ramandt; Bart (Brugge, BE)
|
| Assignee:
|
Agfa Gevaert, N.V. (Mortsel, BE)
|
| Appl. No.:
|
657111 |
| Filed:
|
June 3, 1996 |
Foreign Application Priority Data
| Current U.S. Class: |
430/7; 430/428 |
| Intern'l Class: |
G02B 005/20 |
| Field of Search: |
430/7,428,429
349/106
|
References Cited
U.S. Patent Documents
| 5206119 | Apr., 1993 | Kuse et al. | 430/372.
|
| 5462822 | Oct., 1995 | Roosen et al. | 430/7.
|
| Foreign Patent Documents |
| 3085984 | Jan., 1986 | AU.
| |
| 0072775 | Feb., 1983 | EP.
| |
| 0615161 | Sep., 1994 | EP.
| |
| 1392134 | Apr., 1975 | GB.
| |
Other References
Abstract of JP 3-209202, "Color Filter", Mochizuki et al. (Sep. 1991).
|
Primary Examiner: McPherson; John A.
Attorney, Agent or Firm: Breiner & Breiner
Claims
We claim:
1. A method for manufacturing a multicolour filter array element, firmly
associated with a transparent electrode layer in a multicolour liquid
crystal display device, comprising the steps of:
(i) exposing a photographic silver halide colour material comprising a
plurality of differently spectrally sensitive silver halide emulsion
layers on a glass support, by a single step multicolour pixelwise
exposure,
(ii) colour processing said exposed colour material producing thereby in
each silver halide emulsion layer a differently coloured pixel pattern,
(iii) coating said colour processed colour material at its silver halide
emulsion layer side with a hydrophobic water-impermeable organic resin
layer,
(iv) curing said organic resin layer by heating said layer at temperatures
between 100.degree. C. and 250.degree. C.,
(v) depositing a transparent electrode layer on said organic resin layer,
and
(vi) coating an alignment layer on top of said transparent electrode layer,
characterized in that said colour processing comprises the steps of:
(a) developing said exposed colour material,
(b) bleaching and fixing said developed material,
(c) rinsing said material with water, and
(d) treating said material in an aqueous solution consisting essentially of
a member selected from the group of single salts and mixed salts of a
group III metal.
2. A method according to claim 1, wherein said group III metal is a member
selected from the group consisting of Al, Ga and In.
3. A method according to claim 1, wherein said group III metal is Al.
4. A method according to claim 1, wherein said aqueous solution contains
said member selected from the group consisting of single salts and mixed
salts of a group III metal in a concentration between 0.01 and 1
mole/liter.
5. A method according to claim 1, wherein said aqueous solution contains
said member selected from the group consisting of single salts and mixed
salts of a group III metal in a concentration between 0.05 and 0.2
mole/liter.
6. A method according to claim 1, wherein said aqueous solution contains a
member selected from the group of Al(NO.sub.3).sub.3, Ga(NO.sub.3).sub.3,
In(NO.sub.3).sub.3, Al.sub.2 (SO.sub.4).sub.3, and potassium aluminum
sulfate.
Description
1. FIELD OF THE INVENTION
This invention relates to a method for processing a colour photographic
material. It also relates to a method for the production of a multicolour
filter array element, comprising processed colour photographic material.
2. BACKGROUND OF THE INVENTION
Liquid crystal display devices are used nowadays in numerous applications
such as clocks, household appliances, electronic calculators, audio
equipment, etc. There is a growing tendency to replace cathode ray tubes
by liquid crystal display devices being favoured for their smaller volume
and lower power consumption. In some applications like e.g. laptop
computers and pocket TV's liquid crystal display devices are even without
competition.
High definition television in its ultimate version will require screen
diagonals exceeding 50 inch (see P. Plezhko in the periodical Information
Display September 1991, Vol. 7 no. 9, p. 19 a.f.). Although not yet in
existence CRT-based 50 inch screens can be expected to be very impractical
because of their weight and size. Liquid crystal technology is basically
able to produce high definition television (HDTV) screens with moderate
weight and size.
Liquid crystal display devices generally include two spaced glass panels,
which define a sealed cavity, which is filled with a liquid crystal
material. The glass plates are covered with a transparent electrode layer
which may be patterned in such a way that a mosaic of picture elements
(pixels) is created.
Full colour reproduction is made possible by the use of a colour filter
array element inside the liquid crystal display device.
Two addressing systems are used to drive the display: either a passive
system or an active system.
According to the passive system in the liquid crystal device the two
electrode layers are patterned in a regular array of stripes. The stripes
on one plate are perpendicular to those on the other plate.
The application of a voltage across two opposing stripes causes a change in
the optical properties of the liquid crystal material situated at the
crossing point of the two stripes, resulting in a change of the light
transmission through the energized picture element called pixel.
According to the active system, which greatly improves the performance of
the liquid crystal display device, each pixel has its own individual
microelectronic switch, which means that such a microswitch is connected
to an individual transparent pixel electrode, the planar size of which
defines the size of the pixel. The microswitches are individually
addressable and are three-terminal or two-terminal switching elements.
Three-terminal switches are formed by thin film transistors (TFT). These
transistors are arrayed in a matrix pattern on a glass plate which
together with a glass plate carrying a transparent uniform (non-patterned)
electrode layer forms a gap filled with the liquid crystal material.
With a diode or a similar two-terminal switching device the transparent
electrode layer must be patterned.
To impart colour reproduction capability to the liquid crystal display
device a colour filter array element is provided on one of the two glass
plates. In an active matrix display, examples of which are described in
U.S. Pat. Nos. 5,081,004 and 5,003,302, this is usually the glass plate
opposite the glass plate carrying the switching elements.
A colour filter array for full colour reproduction consists of red, green
and blue patches arranged in a given order. For contrast improvement the
colour patches may be separated by a black contour line pattern
delineating the individual colour pixels (ref. e.g. U.S. Pat. No.
4,987,043).
In order to prevent loss of effective voltage over the liquid crystal
material the colour filter is preferably kept out of the electrical
circuit which means that the transparent electrode is deposited on top of
the colour filter array element.
Several techniques for making colour filter array elements have been
described in the prior art.
A first widely used technique operates according to the principles of
photolithography (ref. e.g. published EP-A 0 138 459) and is based on
photo-hardening of polymers e.g. gelatin. Dichromated gelatin, doped with
a photosensitizer is coated on glass, exposed through a mask, developed to
harden the gelatin in the exposed areas and washed to remove the unexposed
gelatin. The remaining gelatin is dyed in one of the desired colours. A
new gelatin layer is coated on the dyed relief image, exposed, developed,
washed and dyed in the next colour, and so on. By that wash-off and dying
technique four complete operation cycles are needed to obtain a red, green
and blue colour filter array having the colour patches delineated with a
black contour line. As an alternative dyeable or coloured photopolymers
are used for producing superposed coloured photoresists. In the repeated
exposures a great registration accuracy is required in order to obtain
colour filter patches matching the pixel-electrodes.
In a modified embodiment of said photoresist technique organic dyes or
pigments are applied by evaporation under reduced pressure (vacuum
evaporation) to form a coloured pattern in correspondence with photoresist
openings ›ref. Proceedings of the SID, vol. 25/4, p. 281-285, (1984)!. As
an alternative a mechanical precision stencil screen has been used for
pattern wise deposition by evaporation of dyes onto a selected substrate
(ref. e.g. Japan Display 86, p. 320-322.
According to a second technique dyes are electrodeposited on patterned
transparent electrodes from a dispersion of curable binder polymers,
dispersing agents and coloured pigments. For each colour a separate
deposition and curing step is needed.
According to a third technique said red, green and blue dyes are deposited
by thermal transfer from a dye donor element to a dye-receiving element,
comprising a transparent support, e.g. glass plate, having thereon a
dye-receiving layer. Image-wise heating is preferably done by means of a
laser or a high intensity light flash. For each colour a separate dye
transfer step must be carried out.
According to a fourth technique as described e.g. in U.S. Pat. No.
4,271,246 a method of producing a multicolour optical filter comprises the
steps of
(1) exposing a photographic material comprising a support and a single,
i.e. one, black-and-white silver halide emulsion layer to light through a
first pattern;
(2) developing the exposed emulsion layer with a first coupler-containing
colour developer to form a pattern of a first dye; then
(3) exposing an unexposed portion of said emulsion layer to light through a
second pattern;
(4) developing the exposed area with a second coupler-containing colour
developer to form a pattern of a second dye;
(5) repeating exposure and development to form patterns containing dyes of
third and optionally subsequent colours, thereby to form colour patterns
of at least two colours; and subjecting the product to a silver removal
treatment after the final colour development step.
All the above described techniques have in common that they require at
least three (four if the black contour pattern requires a separate step)
treatment steps, and some of them require very costly exposure apparatuses
to reach the desired level of registration.
By the large number of production steps and the required accuracy the
manufacturing yields, i.e. the percentage of the colour filter array
elements made in the factory which meet quality control standards are
exceptionally low. The very costly investments could be brought down when
the filter production could be simplified and yet high quality maintained.
When using a multilayer colour photographic silver halide material for
multicolour filter production comparable to colour print film used in the
motion picture film industry the above mentioned problems related to image
registration and large number of processing steps can be avoided. From one
colour negative an unlimited number of colour positives on film can be
produced at a very high rate. Only one exposure for each positive is
needed. A great number of exposed positives can be chemically treated at
the same time in the same machine. This makes the whole process very
attractive from the viewpoint of yield and investment. Such process
operating with a negative colour image as original to form a complementary
colour pattern on a glass substrate has been described already in
published Japanese patent application (Kokai) 60-133427.
EP-A 396 824 relates to a process for the production of a multicolour
liquid crystal display device comprising a liquid crystal layer
essentially consisting of nematic crystals in twisted or supertwisted
configuration or smectic C (chiral smectic) ferroelectric liquid crystals
wherein the liquid crystal molecules are aligned in such a way that said
layer shows an electrically controllable rotation of the polarization
plane of the light incident on the display. Said liquid crystal layer
together with a multicolour filter element is arranged between front and
rear transparent electrodes for altering pixelwise the electric field over
the liquid crystal layer and said electrodes are associated respectively
with a front and rear light polarizer element. Said process comprises in
consecutive order the steps of:
(1) providing a photographic print material that contains on a glass
support a plurality of differently spectrally sensitive silver halide
emulsion layers,
(2) subjecting said print material to a single step multicolour pixelwise
exposure,
(3) colour processing said exposed print material producing thereby in each
silver halide emulsion layer a differently coloured pixel pattern,
(4) coating said colour processed print material at its silver halide
emulsion layer assemblage side with a hydrophobic water-impermeable
organic resin layer, and
(5) depositing by vacuum-coating one of said electrodes on said organic
resin layer serving as a covering layer for said silver halide emulsion
layer assemblage.
So, before introducing said multicolour filter in the liquid crystal device
the uppermost emulsion layer of the thus processed photographic print
material is coated with a hydrophobic water-impermeable organic resin to
form a covering layer of said resin thereon, and by vacuum-deposition on
top of the thus-applied resin coating a transparent electrically
conducting (electrode) layer is formed.
Said resin layer on top of the colour filter array provides a good
planarity and prevents the release of volatile substances from the
emulsion layer during vacuum-deposition, e.g. by sputtering, of the
transparent conducting layer. Usually a bake at 150.degree. C. or even
higher is needed to impart by curing a good impermeability to the resin
layer.
In liquid crystal displays of the so-called twisted nematic (TN) type (as
are the majority of active matrix liquid crystal displays) the transparent
uniformly applied electrode and also the patterned electrode are covered
with an alignment layer. This layer usually consists of a heat-cured
polyimide resin. Rubbing this cured layer with e.g. a nylon cloth (ref.
e.g. GB-P 1,505,192) in a given direction causes an orientation of the
liquid crystal molecules near the surface of the layer in the rubbing
direction.
From the preceding it is clear that the multicolour filter array element is
subjected to rather severe heat treatment steps during the manufacture of
the liquid crystal display element. These heating steps may not give rise
to discolouration of the filter and dye fading.
Most dyes formed by a reaction based on the coupling of colour formers with
oxidized colour developer of the p-phenylenediamine type have rather
limited resistance to high temperatures and tend to become yellowish or
brownish, while the blues turn to dark grey.
Since the dyes are formed in a coupling reaction between a colour coupler
and the colour developing substance in its oxidized form, the structure of
the colour developing substance is decisive also for the dye-stability. In
most embodiments of colour development by means of colour couplers
p-phenylenediamine type developing agents are used. In EP-A 459 210
derivatives of p-phenylenediamine yielding dyestuffs with improved
fastness to light are described. Such colour developing substances are
therefore advantageously used in the production of colour filters
subjected later on to radiation and/or thermal treatment.
In EP-application 95200306 filed on Feb. 8, 1995 p-phenylenediamine
derivatives giving more stable dyes after colour development have been
disclosed.
Still the problem of yellowing under heat treatment remain and because the
heat treatment of the colour filters incorporated in LCD is quite severe,
but necessary, the advantages of using a photographic material to produce
the colour filter (simplicity of the process) cannot be fully exploited,
when the yellowing of the processed colour material due to heat is not
diminished.
3. OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the invention to provide a method for processing a
silver halide colour photographic material, comprising at least three
differently spectrally sensitive silver halide emulsion layers, each
sensitive to blue, green and red light respectively, whereby the yellowing
of the processed material, due to an heat treatment is lowered.
It is an other object of the present invention to provide a method for
manufacturing a multicolour filter array element, firmly associated with a
transparent electrode layer in a multicolour liquid crystal display
device, using a developed photographic colour material as multicolour
filter, which manufacture includes heat treatment steps and wherein the
processed colour material is less susceptible to yellowing.
Other objects and advantages will become clear from the detailed
description and examples which are not limitative to the scope of the
present invention.
The objects of the present invention are realized by providing a method for
manufacturing a multicolour filter array element, firmly associated with a
transparent electrode layer in a multicolour liquid crystal display
device, comprising the steps of:
(i) exposing a photographic silver halide colour material comprising a
plurality of differently spectrally sensitive silver halide emulsion
layers on a glass support, by a single step multicolour pixelwise
exposure,
(ii) colour processing said exposed colour material producing thereby in
each silver halide emulsion layer a differently coloured pixel pattern,
(iii) coating said colour processed colour material at its silver halide
emulsion layer side with a hydrophobic water-impermeable organic resin
layer
(iv) curing said organic resin layer by heating said layer at temperatures
between 100.degree. C. and 250.degree. C.
(v) depositing a transparent electrode layer on said organic resin layer
and
(vi) coating an alignment layer on top of said transparent electrode layer,
characterised in that said colour processing comprises the treatment of
said colour processed material in a solution comprising ions of at least
one group III metal.
Preferably said treatment proceeds in a solution comprising ions of at
least one metal selected from the group consisting of Al, Ga and In.
In a further preferred embodiment said treatment proceeds in a solution
comprising Al.sup.3 +-ions originating from single salts or from mixed
salts.
4. DETAILED DESCRIPTION OF THE INVENTION
It has been found that the yellowing by heat of a processed silver halide
colour photographic material, can greatly be enhanced by giving the colour
material a treatment in a solution comprising ions of at least one group
III metal. Especially the treatment in a solution comprising ions of at
least one metal selected from the group consisting of Al, Ga and In has
proven to be beneficial.
It is, for a treatment according to the present invention, preferred to use
a solution comprising Al.sup.3 +-ions originating from single salts or
from mixed salts.
The solution comprising the metal ions, described above, can comprise said
ions in a concentration between 0.01 and 1 mole/liter, preferably between
0.05 and 0.5 mole/liter, more preferably between 0.05 and 0.2 mole/liter.
The solvent for a solution, useful for a treatment according to the present
invention, is preferably an aqueous solvent. The aqueous solvent can
consist of 100% of water, or can consist of water mixed with one or more
polar solvents. The polar solvents are preferably lower alkyl alcohols,
more preferably ethanol or methanol. When a polar solvent is mixed with
water to form the aqueous solution, it is preferred that not more than 50%
by volume of the polar solvent is present.
The solution, for a treatment according to the present invention, can
comprise any surfactant known in the art. It can comprise anionic
surfactants, cationic surfactants as well as non-ionic surfactants.
The treatment with the solution of the metal ions described above, proceeds
preferably after the colour material has been bleached and fixed (this
bleaching and fixing can proceed in a single step, wherein fixing and
bleaching proceed simultaneously.).
A treatment according to the present invention can take from 10 seconds to
10 minutes of time, but preferably is adjusted so as to be between 5% to
50% of the time the material resides in the colour developer.
It is preferred to rinse the material after said bleaching and fixing and
before the treatment in a solution comprising ions of at least one group
III metal.
After the treatment in a solution comprising ions of at least one group III
metal, the colour material can be dried directly, or more preferably the
after a rinsing step. After the treatment of the colour material in a
solution comprising group III metal ions, the material can receive further
treatments, e.g. rinsing, treatment in a hardener solution, etc.
The processing cycle of a colour material, comprising a treatment according
to the present invention can comprise e.g. the steps of: (i) developing,
(ii) rinsing, (iii) bleach/fixing, (iv) rinsing, (v) treatment in a
solution comprising at least one group III metal ion, (vi) rinsing, (vii)
treatment in an hardener solution, (viii) rinsing and (ix) drying.
It is clear that further steps can be added to or some steps omitted from
the processing sequence of a colour material, the processing sequence
still being within the scope of the present invention: it is e.g. possible
instead of having a single bleach/fixing step to replace this single step
by the steps of fixing, bleaching, fixing again and include further
rinsing steps between the fixing, bleaching and fixing steps. It is e.g.
possible to split the single bleach/fixing step in the steps of (iiia)
fixing, (iiib) rinsing, (iiic) bleaching, (iiid) rinsing and (iiie)
fixing. It is e.g. also possible to omit some of the rinsing steps and to
omit the final hardening step. It is also possible to add between the
development step and the first rinsing step a treatment in an acid stop
bath.
The present invention includes thus a method for processing a silver halide
colour material comprising a treatment of said colour processed colour
material in a solution comprising ions of at least one group III metal.
Although the treatment in a solution, as described above, prevents the
yellowing of any colour material known in the art, it is very interesting
to use such a treatment in a method for manufacturing a multicolour filter
array element, firmly associated with a transparent electrode layer in a
multicolour liquid crystal display device, using a developed photographic
colour material as multicolour filter, which manufacture includes heat
treatment steps. This method for producing a multicolour filter array
element, firmly associated with a transparent electrode layer in a
multicolour liquid crystal display device, comprises the steps of:
(i) exposing a photographic silver halide colour material comprising a
plurality of differently spectrally sensitive silver halide emulsion
layers on a glass support, by a single step multicolour pixelwise
exposure,
(ii) colour processing said exposed colour material producing thereby in
each silver halide emulsion layer a differently coloured pixel pattern,
(iii) coating said colour processed colour material at its silver halide
emulsion layer side with a hydrophobic water-impermeable organic resin
layer
(iv) curing said organic resin layer by heating said layer at temperatures
between 100.degree. C. and 250.degree. C.
(v) depositing a transparent electrode layer on said organic resin layer
and
(vi) coating an alignment layer on top of said transparent electrode layer,
and the colour processing comprises the treatment of said colour processed
colour material in a solution comprising at least one group III metal ion.
Such solutions have been described in detail herein above.
In a preferred embodiment the sequence wherein the differently spectrally
sensitive silver halide emulsion layers are applied on a glass support for
a photographic material that is especially useful in the method, according
to this invention, for manufacturing a multicolour filter array element,
is the sequence that is described in EP-A 615 161, which is incorporated
herein by reference. In this application a photographic element is
disclosed, wherein said element comprises on a glass support (i) a silver
halide emulsion layer sensitive to blue light and containing a yellow dye
forming colour coupler, (ii) a silver halide emulsion layer sensitive to
green light and containing a magenta dye forming colour coupler, (iii) a
silver halide emulsion layer sensitive to red light and containing a cyan
dye forming colour coupler, wherein said layer (iii) is most remote from
said support and in each silver halide emulsion layer the equivalent ratio
of silver halide to colour coupler is at least 1.
The amount of silver halide present in each colour coupler containing layer
is adjusted preferably in such a way that in the strongest exposed regions
the colour coupler is completely converted to dye during the colour
development. This means that the equivalent ratio of silver halide to
colour coupler in the colour material should be preferably at least 10%
higher than 1.
A ratio of 1 in equivalent amounts means that for each mole of colour
coupler present in the layer 4 or 2 moles of silver halide are added,
depending on whether the colour coupler is of the 4- or the 2-equivalent
type.
In the transformation of one mole of a 4-equivalent colour coupler into one
mole of dye, 4 moles of oxidized colour developer are involved, which
means that 4 moles of silver halide must be reduced. In the case of a
2-equivalent colour coupler only 2 moles of silver halide are needed for a
complete conversion.
In order to inhibit the diffusion of oxidized developing agent into
neighbouring silver halide emulsion layers said layers are separated by an
intermediary water-permeable colloid layer, e.g. gelatin-containing layer,
comprising a scavenging agent for oxidized developing agent. Suitable
scavenging agents for that purpose are diffusion-resistant hydroquinone
derivatives, preferably containing one or more aliphatic ballast groups
having at least 6 carbon atoms. Such scavenging agents and their use are
described e.g. in
The silver halide emulsion layer may contain any type of light-sensitive
silver halide emulsion, e.g. an emulsion that forms a latent image
primarily on the surfaces of the silver halide grains, or that forms an
internal latent image predominantly in the interior of the silver halide
grains. The emulsions can be negative-working emulsions, e.g.
surface-sensitive emulsions or unfogged internal latent image-forming
emulsions, or positive-working emulsions e.g. direct-positive emulsions of
the unfogged, internal latent image-forming type, the development of which
is conducted with uniform light exposure or in the presence of a
nucleating agent. Further are mentioned direct-positive emulsions of the
pre-fogged type wherein during image-wise exposure chlorine, bromine
and/or iodine is liberated which image-wise destroys the developable
centres created during overall prefogging. Direct-positive emulsions need
only one development (as do negative emulsions).
Reversal silver halide emulsions are not prefogged. Their processing
includes 2 development steps and a fogging step. The first development is
carried out with a black-and-white developer whereby a negative
black-and-white silver image is formed. The remaining silver halide is
made developable by fogging, either physically (by exposure to light) or
chemically. Upon subsequent colour development, bleaching and fixing a
positive colour image is obtained.
By negative-working is meant that the density observed after processing is
proportional to the exposure. By positive-working is meant that the silver
halide emulsions yield upon exposure and development positive images, i.e.
the density is inversely proportional to the exposure.
The applied silver halide can be of the silver chloride, the silver
chloride-bromide, the silver bromide, the silver bromide-iodide or the
silver chloride-bromide-iodide type.
The silver halide can be surface sensitized. Noble metal (e.g. gold),
middle chalcogen (e.g. sulfur, selenium or tellurium), and reduction
sensitizers, employed individually or in combination, are specifically
contemplated. Typical chemical sensitizers are listed in Research
Disclosure December 1989, item 308119, section III.
The silver halide can be spectrally sensitized with dyes from a variety of
classes, including the polymethine dye class, which includes the cyanines,
merocyanines, complex cyanines and merocyanines (i.e. tri-, tetra-, and
polynuclear cyanines and merocyanines) oxonols, hemioxonols, styryls,
merostyryls, and streptocyanines; see said Research Disclosure, section
IV.
Suitable vehicles for the emulsion layers and other layers of the colour
material are described in section IX of said Research Disclosure and
brighteners and antifoggants are described respectively in sections V and
VI, and hardeners for gelatin in section X.
As already mentioned hereinbefore colour filters for liquid crystal
displays normally comprise a repeating pattern of coloured patches as in a
mosaic pattern or may form a pattern of stripes. The coloured patches are
preferably separated by a black contour line, which according to the
present invention is formed by superposed area of the different emulsion
layers wherein on colour-development cyan, magenta and yellow dye is
formed respectively.
According to a preferred embodiment the reflections from the glass plate
back into the multilayer arrangement are eliminated by the presence of a
light-absorbing (anti-halation) layer between the glass substrate and the
first photographic silver halide emulsion layer. This anti-halation layer
must lose its light-absorbing properties during or after processing and
become as clear as possible. To this end one or more dyes are present in
said layer which dyes should be destroyed chemically in one or more
processing liquids or simply be soluble in one or more of the processing
liquids or in the rinse water and be washed out. It is advantageous to use
anti-halation dyes of the non-diffusing type, i.e. dyes that are insoluble
in water and do not migrate to adjacent layers during manufacture. Such is
important when the dyes, due to their spectral or other properties, can
change the photographic properties of the adjacent silver halide emulsion
layers.
Yellow dyes of the non-diffusing type that may serve in decolourizable
anti-halation layers for use in a multicolour colour material according to
the present invention as illustrated in the accompanying drawing are
described in U.S. Pat. No. 4,770,984.
Filter or anti-halation dyes may be present in one or more layers of the
multilayer arrangement to decrease unwanted interlayer reflections and/or
to improve the optical characteristics of individual layers. This practice
is well known to those skilled in the art.
The multilayer arrangement of hydrophilic colloid (gelatin containing)
layers of the present multicolour print material must stick very firmly to
the glass substrate. The glass used for the substrate is e.g. borax glass,
borosilicate glass, lime glass, potash glass, soda glass, crown glass,
flint glass, silica-flint glass, chromium glass, zinc-crown glass or
quartz glass. The glass support has e.g. a thickness in the range of 0.5
to 1.5 mm.
The so-called subbing layers currently used in colour print film on a resin
support cannot be used due to the very different nature of the glass
substrates.
A strong adhesion of the hydrophilic colloid multilayer arrangement to the
glass support can be realized by means of a very thin subbing layer
containing gelatin, a water-soluble inorganic silicon compound like e.g.
sodium silicate (water glass) and a gelatin hardening agent.
An equally strong adhesion can be obtained without a subbing layer by the
addition to the first layer, which in a preferred embodiment is a
gelatin-containing light-absorbing anti-halation layer, of an organic
silicon compound such as an epoxysilane and a hardening agent for gelatin.
When said layer after being freshly coated is treated at a temperature in
the range of 34.degree. to 40.degree. C. and at a relative humidity in the
range of 70 to 85% the adhesion of said subbing layer towards a
gelatin-containing layer such as a gelatin-silver halide emulsion layer is
much improved. Particularly suitable subbing layers on the basis of
organic silicon compounds are described in U.S. Pat. No. 3,661,584 and
GB-P 1,286,467.
The pixelwise exposure of the multicolour print material according to the
present invention can be performed in several ways.
For example, the exposure may proceed in a single step through a
multicolour master, in a plurality of steps with light of different colour
(blue, green and red) through a pitchwise shiftable black-and-white mask
or simultaneously or subsequently by means of pixelwise modulated laser
beams of different colour, blue, green and red.
A convenient method for manufacturing the colour filters for use according
to the present invention, especially in mass-production when a great
number of them is needed, is to carry out the exposure in a single step
through a multicolour master.
When used in conjunction with a negative type multilayer silver halide
colour material the master must be a coloured negative master, whereas a
coloured positive master is needed when a direct positive or reversal type
multilayer silver halide colour material is involved.
A coloured negative master has predominantly yellow-, magenta- and cyan
coloured pixels at the places corresponding respectively with the blue,
green and red pixels on the colour filter array element.
In said single step exposure using a white light source the coloured master
is in close or near contact with the multilayer silver halide colour
material from which a colour filter is to be made, the gelatin layers of
both materials facing each other. By said single step exposure
simultaneously latent images in the 3 light-sensitive differently
spectrally sensitive silver halide emulsion layers are formed.
Deviation from the desired spectral transmission characteristics of the
filter area may be corrected by inserting in the white light beam filters
changing the proportion of red, green and blue transmitted by the
multicolour master.
The negative and positive masters may be made by means of other recording
materials than silver halide emulsion type materials.
For example, the multicolour master may be made by photolithography,
vacuum-deposition or electrodeposition of dyes, thermal transfer of dyes,
electro(photo)graphy with coloured toner or ink-jet printing with coloured
inks.
After processing the silver halide colour filter is covered with a
protective resin layer which in the production of a multicolour filter
associated with an electrode layer has to be present.
Since gelatin is a hydrophilic polymer it contains still a small amount of
water even after thorough drying. Minor quantities of water may not enter
the liquid crystal cell since they profoundly disturb the operation of the
liquid crystal display. Moreover, during the application of the electrode
layer by vacuum-deposition water or other volatile substance may not
escape from the gelatin-containing layers and has to be kept blocked by a
protective impermeable resin layer on top of the uppermost
colour-developed silver halide emulsion layer of the colour filter. In the
manufacture of a liquid crystal display according to the present invention
heat-curable resins are used for producing said impermeable layer.
Examples of heat-curable organic resins and curing agents therefor are
described by Ernest W. Flick in "Handbook of Adhesive Raw
materials"--Noyens Publications--Park Ridge, N.J., USA (1982). Polyimide
resins that can be heat-cured are e.g. the photo-curable polyimide resins
disclosed in U.S. Pat. No. 4,698,295. Further are mentioned epoxy resins
that can be heat-cured with amines thermally set free from an amine
precursor e.g. ketimine which on reacting with water yields an amine ›ref.
The Chemistry of Organic Film Formers by D. H. Solomon, John Wiley & Sons,
Inc. (1967), p.190!.
The water-impermeable hydrophobic organic resin layer may be coated from a
liquid composition containing (an) evaporatable solvent(s) or may be
applied onto the processed multicolour material by lamination using e.g. a
heat-curable layer sandwiched originally between a polyethylene film and a
protective cover sheet analogously to the type of material described in J.
photogr. Sci., 18, 150 (1970).
The wet strength of the colour processed gelatin containing silver halide
emulsion layer assemblage before coating with the organic resin layer in
step (4) of the present invention statement can be greatly improved as
described in published EP-A 0 396 824 by a treatment with an aqueous
composition containing the self-cross-linking reaction product of:
(i) an epihalohydrin or an Alpha-dihalohydrin,
(ii) a water-soluble polyamide, and
(iii) a water-soluble polyamine containing at least two nitrogen atoms
separated by at least three carbon atoms and optionally also by at least
one oxygen or sulphur atom and having at least two hydrogen atoms attached
to different nitrogen atoms. Said self-cross-linking reaction product may
form itself a water-impermeable hydrophobic organic resin layer serving as
covering layer or as subbing layer for another outermost water-impermeable
organic resin layer.
The preparation of the above defined self-cross-linking reaction product is
given in GB-P 1 269 381, wherein said product is described for improving
the wet strength of paper.
A transparent conductive layer forming the electrode layer is applied to
the impermeable resin layer by known techniques, e.g. a transparent indium
tinoxyde (ITO) layer is applied by vacuum-deposition.
Although the multicolour filter array elements prepared according to the
present invention are very well suited for the production of active matrix
liquid crystal displays there use is not restricted to that type of
displays. They can be incorporated likewise in passive matrix liquid
crystal displays, especially in supertwisted nematic (STN), double
supertwisted nematic (DSTN), retardation film supertwisted nematic
(RFSTN), in ferroelectric (FLC) , guest host (GH), polymerdispersed (PF),
polymer network (PN) liquid crystal displays, and so on. They can further
be incorporated in emissive displays like electroluminescent displays, CRT
devices and in charge coupled device (CCD) cameras.
The following examples illustrates the present invention without however
limiting it thereto.
EXAMPLES
All formulas are given after the description of the various layers
comprised in the material.
Following layers were coated in the order given on sodalime glass with a
thickness of 1.5 mm to form a colour photographic material.
Anti-halation layer
A non-diffusing yellow dye of formula YD, was dispersed in gelatin. To this
dispersion epoxysilane E (structure defined hereinafter) acting as an
adhesion promoter was added. The coverages of yellow dye YD, gelatin and
epoxysilane E were 0.5, 1.5 and 0.1 g/m.sup.2 respectively.
Blue sensitive layer
A 100% silver chloride emulsion with an average grain size of 0.4 .mu.m was
sensitized to blue light with a spectral sensitizing agent of formula SB.
A yellow dye forming coupler of formula Y1 was added to this emulsion.
The amounts of silver halide, gelatine and colour coupler Y1 were 0.57,
3.30 and 1.0 g/m.sup.2 respectively.
First intermediate layer
A substance of formula SD, capable of scavenging oxidized colour developing
agent was dispersed in gelatin and coated at a coverage of 0.08 g
SD/m.sup.2 and of 0.77 g gelatine/m.sup.2.
Green sensitive layer
A silver chloride-bromide (90/10 molar ratio) emulsion with an average
grain size of 0.12 .mu.m was sensitized to green light with a spectral
sensitizing agent of formula SG. A magenta dye forming coupler of formula
M1 was added to this emulsion.
The amounts of silver halide, gelatin and colour coupler M1 were 0.71, 2.8
and 0.53 g/m.sup.2 respectively.
Second intermediate layer
This layer has the same composition as the first intermediate layer.
Red sensitive layer
A silver chloride-bromide (90/10 molar ratio) emulsion with an average
grain size of 0.12 .mu.m was sensitized to red light with a spectral
sensitizing agent of formula SR. A cyan dye forming coupler of formula C1
was added to this emulsion.
The amounts of silver halide, gelatin and colour coupler C1 were 0.49, 4.5
and 0.95 g/m.sup.2 respectively.
Yellow, magenta and cyan water-soluble dyes, acting as accutance dyes were
present at an appropriate coverage in the blue, green en red sensitive
layer respectively and hydroxytrichlorotriazine acting as hardening agent
was present in the red sensitive layer at a coverage of 0.035 g/m.sup.2.
In the following Table 1 the silver halide to colour coupler ratio in
equivalent amounts is given for the three light-sensitive layers of the
material. The coverages of the colour couplers, expressed in
mmoles/m.sup.2, are also given.
TABLE 1
__________________________________________________________________________
Silver halide colour coupler (eq.)
mmol colour coupler/m.sup.2
__________________________________________________________________________
Blue sens. layer
1.2 1.4
Green sens. layer
1.2 0.9
Red sens. layer
1.3 1.1
__________________________________________________________________________
CHEMICAL FORMULAS
__________________________________________________________________________
##STR1## YD
##STR2## SB
##STR3## Y1
##STR4## SD
##STR5## SG
##STR6## M1
##STR7## SR
##STR8## C1
##STR9## E
__________________________________________________________________________
Unexposed sheets of the material were processed in the processing sequence:
developing in a developer with composition as given herebelow:
______________________________________
Sodium sulphite (anhydrous)
4 g
4-amino-3-methyl-N,N-diethylaniline hydrochloride
3 g
sodium carbonate (anhydrous)
17 g
sodium bromide 1.7 g
sulphuric acid 7 N 0.62 ml
water up to 1000 ml
______________________________________
After development each sheet was treated in an acid stop bath prepared by
adding water up to 1 l to 50 ml of sulphuric acid 7N. The treatment with
stop bath was followed by 2 minutes rinsing in plain water followed by a 2
minutes fixing in an aqueous solution having the following composition:
______________________________________
58% aqueous solution of (NH.sub.4).sub.2 S.sub.2 O.sub.3
100 ml
sodium sulphite (anhydrous)
2.5 g
sodium-hydrogen sulphite (anhydrous)
10.3 g
water up to 1000 ml
______________________________________
The treatment with fixing liquid was followed by a 2 minutes rinsing in
plain water followed by a 3 minutes bleaching in an aqueous solution
having the following composition:
______________________________________
potassium hexacyanoferrate (III) (anhydrous)
30 g
sodium bromide (anhydrous)
17 g
water up to 1000 ml
______________________________________
Thereupon each sheet was treated with the fixing liquid again and rinsed
for 3 minutes with plain water. After this rinsing each sheet, except a
comparative sheet, was treated in a solution comprising ions of at least
one a group III in a concentration of 0.1 mole/liter for 5 minutes.
Sheet 1: no treatment (comparative)
Sheet 2: treatment in a solution of 0.1 mole/liter of Al(NO.sub.3).sub.3
Sheet 3: treatment in a solution of 0.1 mole/liter of Ga(NO.sub.3).sub.3
Sheet 4: treatment in a solution of 0.1 mole/liter of In(NO.sub.3).sub.3
Sheet 5: treatment in a solution of 0.1 mole/liter of Al.sub.2
(SO.sub.4).sub.3
Sheet 6: treatment in a solution of 0.1 mole/liter of
Potassiumaluminiumsulfate.
Afterwards the sheets were rinsed.
Finally each sheet was treated with an aqueous solution having a pH of 9
and containing per liter 20 ml of a 40% aqueous solution of formaldehyde
serving as hardening agent.
The sheet were submitted to a heat treatment at 200.degree. C. during 60
minutes. The density increase of the fog, i.e. AD of a non-exposed sheet
before and after the heat treatment, were measured on a transmission
densitometer behind a blue filter.
The water absorption before and after the heat treatment were measured
gravimetrically. A dry sample of the material was accurately weighted (W1)
and then without exposure processed as described above, but taken out of
the processing apparatus before the dryer. The processed, but not dried
sample of the material was weighted again (W2) and after drying the sample
was weighted again (W3). The difference between W2 and W3 was the water
absorption of the sample, i.e. the amount of water per m.sup.2 that has to
be evaporated in the dryer.
The results are given in table 2.
TABLE 2
______________________________________
.DELTA.Density
Waterabs*.
Waterabs*.
of the
Sheet number before heat
after heat
fog
______________________________________
1. (comparative)
16.63 7.06 0.42
2. (A1(NO.sub.3).sub.3)
16.63 9.07 0.27
3. (Ga(NO.sub.3).sub.3)
16.65 8.07 0.27
4. (In(NO.sub.3).sub.3)
17.64 9.58 0.34
5. (A1.sub.2 (SO.sub.4).sub.3)
15.88 9.01 0.27
6. Potassiumaluminiumsulfate
20.41 8.79 0.30
______________________________________
*in g/m.sup.2 -
It is clear that the treatment in a solution, comprising ions of at least
one group III metal does not influence the water absorption of the
material.
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